Re: [-] drop_caches-add-some-documentation-and-info-messsge.patch removed from -mm tree

[KOSAKI Motohiro <kosaki.motohiro@gmail.com>]

(7/12/13 7:50 AM), Michal Hocko wrote:
> On Thu 11-07-13 14:50:34, Andrew Morton wrote:
>> On Thu, 11 Jul 2013 09:36:44 +0200 Michal Hocko <mhocko@suse.cz> wrote:
>>
>>> On Wed 10-07-13 13:25:03, Andrew Morton wrote:
>>> [...]
>>>> This patch was dropped because it has gone stale
>>>
>>> Is there really a strong reason to not take this patch?
>>
>> I flushed out a whole bunch of MM patches which had been floating
>> around in indecisive limbo.
>>
>> I don't recall all the review issues surrounding this one.
>
> Kosaki was concerned about annoying number of messages if somebody drops
> caches too often (https://lkml.org/lkml/2010/9/20/450). As I noted in
> the changelog
> "
>      Kosaki was worried about possible excessive logging when somebody drops
>      caches too often (but then he claimed he didn't have a strong opinion on
>      that) but I would say opposite.  If somebody does that then I would really
>      like to know that from the log when supporting a system because it almost
>      for sure means that there is something fishy going on.  It is also worth
>      mentioning that only root can write drop caches so this is not an flooding
>      attack vector.
> "
>
> Kosaki then Acked the patch.
>
> You were worried (http://lkml.indiana.edu/hypermail/linux/kernel/1210.3/00605.html)
> about people hating us because they are using this as a solution to
> their issues. I concur that most of those are just hacks that found
> their way into scripts looong time agon and stayed there.
>
> Boris then noted (http://lkml.indiana.edu/hypermail/linux/kernel/1210.3/00659.html)
> that he is using drop_caches to make s2ram faster but as others noted
> this just adds the overhead to the resume path so it might work only for
> certain use cases so a user space solution is more appropriate and
> Boris' use case really sounds valid.
>
> As a compromise I can lower the log level. Would KERN_INFO work for
> you? Or even KERN_DEBUG?
>
> I still find printk less intrusive than fiddling with vmstat counters.

Michal,

It's ok to go IMHO. However, please open new thread w/ a rebased patch. Many developers
don't pay attention a lot to -mm automatic notifications.

Thanks.


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